While advances in Parkinson's disease have been established in recent years, the pathogenesis of the disease is still not well understood. The primary goal of this project is to quantify how complex multijoint movement is impaired in Parkinsonian patients, thereby providing a better understanding of how motor control principles are compromised. Our working hypothesis concerning PD patients is that much of their difficulty with complex movements arises from their inability to coordinate body segments. We use a trunk-assisted prehension task and analyze trunk, arm, and aperture synchronization when speed, accuracy, sequencing of segments, and visual feedback constraints are imposed. We will analyze body segment synchronization, relative timing, spatial invariance, and synergies. Collectively, the results from these experiments will allow us to better understand how PD affects movement coordination patterns during the performance of complex actions. Comparisons of 'off' vs. 'on' states in Parkinson's disease patients may help determine if coordination impairments share a common levodopa basis. The experiments proposed are systematic, novel and use proven methodology. The proposed research should advance understanding of the fundamental principles that guide the coordination of multijoint movements in normal subjects. It will also increase understanding of the ways in which Parkinson's disease patients are restricted in the use of these principles. The results from four experiments should be useful to both the basic neuroscientist and clinical science communities, reducing the gap between fundamental knowledge of neural mechanisms and therapeutic intervention.